[Healeys] oil pump

Tue Oct 30 17:24:38 MDT 2018

Well then please explain to me how a Bugeye I owned in 1971 would drop from 60 PSI at speed to 40 PSI over a period of time.  When I checked the oil it was a quart low.  Adding a quart, the "at speed" pressure returned to 60 PSI.  I mean it was great to have a low oil indicator like that, but I never understood how it worked.
Mike MacLean 

    On Tuesday, October 30, 2018 2:22 PM, Michael Salter <michael.salter at gmail.com> wrote:

 Yes, absolutely true Bob. 
Decreasing oil pressure can certainly be an indicator of increasing clearances.
M

On Tue, Oct 30, 2018 at 12:22 PM Bob Spidell <bspidell at comcast.net> wrote:

  re: "... delivery pressure itself is not that important and is really just an indicator that oil is being delivered to the bearings ..." Pressure is useful as a trend indicator.

 On 10/30/2018 8:54 AM, Michael Salter wrote:

  I have a book "Repco Engine Service Manual" produced by Repco of Repco-Brabham fame that I use as my bible for engine building. 
  On the subject of oil pressure it states that delivery pressure itself is not that important and is really just an indicator that oil is being delivered to  the bearings. 
  Of much greater importance is "thin film pressure" which is generated by the engine forces on a bearing which can be as high as 8000 p.s.i. at high RPM  and is determined by the oil type and temperature, and the engine design. Based upon this I believe that concentrating on having good oil pressure at idle is wasted effort. What is important is that the engine has some pressure  at idle but good pressure in the normal operating range. 
  A pump which puts out a huge volume uses excessive horsepower and can result in accelerated wear of the pump drive. 
  M

  On Tue, Oct 30, 2018 at 11:30 AM Bob Spidell <bspidell at comcast.net> wrote:

  I'll offer what I know/have heard*.  I have the 'high capacity' type in my BJ8, which is what the DWR techs/sales people recommended for a road car.  Older 6-cyl cars had a rotor type pump.  They (the rotor type) are supposed to be more efficient--i.e. they pump more oil--at lower RPMs.  At some point it was discovered, probably from service bay repairs, that this type of pump put an excessive shear load on the bevel gears on the cam  that drive the pump, causing them to wear out.  Later cars started getting the gear type pump, which is less efficient at lower RPMs but puts less of a load on the cam, and is probably less expensive to manufacture as well (esp. if the gears are the sintered iron variety).  I think the bevel gears on the cams were re-engineered, IIRC they got an additional tooth to spread the load.
  The Welch HC pump is the rotor type.  I did a full engine rebuild and installed the DWR HC pump; I didn't notice any pressure change worth mentioning--I 'gained' 15 PSI at idle when I had my gauge overhauled--but the 'high capacity' I believe refers to volume rather than pressure (which, of course, is mostly dictated by engine speed).   The 'standard type' pump is a gear type, hence it's more appropriate for high-RPM race engines as pump flow is proportional to RPM, and at 6K RPM or more you'll get plenty of oil with less load from the gear type. I'm not positive, but if you look at the photos closely, you can see the 'gallery plug' on the top of the case.  I suppose it allows inspection of the innards of the pump without having to break the case.  I believe it's threaded so not likely to pop out.  If you're getting a new pump you'll likely need a new drive shaft and, surprisingly, DWR sells it cheaper than our (US) vendors sell it at (I  think they might import the DWR shaft).
  * apply appropriate grains of salt

 Bob

 On 10/30/2018 5:12 AM, simon.lachlan at alexarevel.plus.com wrote:

  Hi, Has anyone got the Denis Welch oil pump ENG672M? See:- https://www.bighealey.co.uk/performance-parts/austin-healey/engines/3000-bottom-end?page=3 
Their text:- “Heat treated castings for longer life and removable gallery plugs to be sure it is clean are advantages of both types of oil pumps we offer. We recommend the high capacity for all road engines using a standard type crank up to 6000 rpm and the standard  pump for race engines, steel cranks or anything over 6000 rpm. Both are precision machined and assembled in-house to control the highest quality.
 - ENG672 is the standard type.
 - ENG672M is the high capacity pump.”
 What are “removable gallery plugs”? Is it just me or is the above a bit counter-intuitive? “High capacity” for road cars and “standard” for race engines? Surely the highest capacity is needed where the engine is working hardest ie racing?  And don’t I remember that, with the standard BMC pumps, the older type is reckoned to be better than the newer type? Is this something similar to Denis Welch’s two pumps? Anyhow, if anyone’s got one…..what’s it like? Did the oil pressure improve at all? I’m guessing that most people will have fitted one as part of a big rebuild thus they won’t have straightforward “before and after” comparisons. I’m thinking of fitting mine to my engine as part of a small winter project and hope I can squeeze a few  more psi into the system.  Thanks, Simon  

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